>>> On 21.06.12 at 15:10, Wei Wang <wei.wang2@xxxxxxx> wrote: > On 06/21/2012 02:45 PM, Jan Beulich wrote: >>>>> On 21.06.12 at 14:28, Wei Wang<wei.wang2@xxxxxxx> wrote: >>> AMD IOMMU is an independent pci-e endpoint, and this function will not >>> be used for other purposes other than containing an iommu. So I don't >>> see that iommu will share bdf value with other devices. >> >> The question is not regarding bdf, but regarding whether under >> the same seg:bus:dev there might be multiple functions, one of >> which is the IOMMU, and if so, whether the IOMMU would be >> guaranteed to have a non-zero function number. > > In a real system (single or multiple iommu), amd iommu shares the same > device number with north bridge but has function number 2.. (e.g > bus:00.2) Howerver according to spec, it does not guaranteed to have > non-zero function number. So what is the problem you see if iommu uses > fun0 on a multi-func device? If it's on func 0 and gets hidden completely (as done by your partial patch), other functions won't be found when scanning for them (because secondary functions get looked at only when func 0 actually exists, as otherwise evaluating the header type register is invalid). Jan -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
